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The effect of nutrition and growth on
sheepmeat eating quality
Nutrition and finishing
Good nutrition and finishing are critical in defining
sheepmeat eating quality in the period leading up to
slaughter. Given the potential for good eating quality cuts
from all sheepmeat categories (lamb, hogget and mutton), it
is important those animals are well nourished and managed.
during periods of active growth, the ‘turnover’ of collagen in
the body (the structural protein that dominates connective
tissue) increases. For this reason, the hardening of
connective tissue is slower. With reduced hardening, the
background toughness in meat will be reduced.
Growth and weight gain
For best eating quality, animals
animals should
should be
be gaining
gaining weight
weight up
up
until slaughter. The
the growth rate
rate in
in the
the two
two weeks
weeks prior
prior to
to
slaughter should be a minimum
minimum of
of 100g
100g per
per day.
day. Good
Good
for Merino
Merinomeat
meat
feeding is particularly important for
production ininthe
production
thetwo
twoweeks
weeksprior
priortotoslaughter.
slaughter.Merino
Merino
sheep and lambs should be
be growing
growing at
at aa minimum
minimum of
of 150g
150g
per day during this period.
period.
Good finishing optimises the amount
amount of
of muscle
muscle and
and
intramuscular fatfatleading
intramuscular
leadingtotomore
moretender
tendermeat
meatand
and
resulting in increased flavour and
and juiciness.
juiciness. Muscle
Muscle tissue
tissue
comprises soft muscle fibres surrounded
surrounded by
by stronger
stronger
in toughness
toughness as
as the
the
connective tissue fibres, which increase
increase in
animal ages. Poorly nourished animals
animals that
that are
are losing
losing
weight will use muscle fibres
fibres and
and intramuscular
intramuscular fat
fat to
to
connective tissue
tissuefibres
fibres
nourish the rest of the
the body,
body, but the connective
remain unchanged. Consequently, poorly finished sheep are
likely to produce tougher meat.
The effect of finishing on eating
quality
research has shown that the type of finishing system has
little effect on eating quality, provided sheep
are gaining weight before slaughter and they
are finished to a fat score of 2 or above. this
will ensure adequate intramuscular fat (4-5%)
for effective juiciness and flavour. if
Key points
• For optimum eating quality results, lambs should be
gaining at least 100g/day for crossbreds and 150g/day for
Merinos.
• Lamb and sheep should be finished to a minimum fat
score of 2
• the type of finishing system has little effect on eating
quality, provided that sheep are gaining weight before
slaughter.
• diets that result in weight loss in the weeks before
slaughter cause meat quality problems.
• Stress prior to slaughter can reduce levels of muscle
glycogen.
• reduced glycogen will increase muscle pH and cause
dark cutting meat.
If
intramuscularfatfatfalls
fallsbelow
below3%,
3%,consumers
consumerswill
willrate
ratemeat
meat
intramuscular
lacking flavour.
flavour.
as dry and lacking
Good quality pasture is just as effective as concentrate
based diets for producing high quality meat. diets that are
very high in cereal grains, fed for prolonged periods, may
cause eating quality problems such as off flavours and soft
fat.
Good finishing optimises
muscle glycogen
Glycogen is animal starch or sugar and is held in reserve for
vigorous muscular activity. Good finishing optimises muscle
glycogen levels at slaughter leading to better colour, flavour
and shelf life. Optimising glycogen is a combination of good
pre-slaughter nutrition and reducing stress in the immediate
pre-slaughter period.
every animal has a certain amount of energy contained in
its muscles in the form of glycogen. Once the animal is
dead, the muscle glycogen is converted to lactic acid, which
causes pH to fall. the glycogen bucket diagram in figure 1
shows this relationship.
19
3
Figure 1: Glycogen bucket
NUTRITION
TRANSPORT
MUSCLE
GLYCOGEN
HANDLING
STRESS
Nutrition provided for the animal is the energy that goes into
the bucket. the holes in the bucket represent the factors
that use up energy, such as exercise or stress. these
factors will always be present in some form, but it is
important to minimise their impact. that is, to keep the
‘holes’ in the bucket as small as possible.
Low levels of muscle glycogen in the live animal cause high
pH meat (above 5.70), which has an unattractive dark
colour, is tougher, takes longer to cook, and has a reduced
shelf life.
Good nutrition reduces the risk of slaughter animals
developing high pH. Nutrition, sufficient to reduce the risk of
the high pH condition in sheep, can be defined as a weight
gain of at least 100g per day (150g per day for Merinos),
and results in a high and normal concentration of glycogen
in lean muscle tissue. the normal and ideal concentration in
sheep is around 1.5g/100g of lean muscle weight.
if the concentration of glycogen in lean muscle tissue falls
below a threshold concentration (around 0.8g/100g), the pH
of the resulting meat becomes higher than normal.
Poor nutrition and stress as a result of poor handling during
mustering, yarding and transport will increase the rate of
glycogen loss.
For more information
www.mla.com.au/msa or 1800 111 672
Level 1, 165 Walker Street
North Sydney NSW 2060
Ph: +61 2 9463 9333
Fax: +61 2 9463 9393
www.mla.com.au
MLa makes no representation as to the accuracy of any information or advice contained in this document and excludes all
liability, whether in contract, tort (including negligence or breach of statutory duty) or otherwise as a result of reliance by any
person on such information or advice.
4
Reprinted September
September 2012
2012
reprinted
ISBN: 1
iSBN:
1 74036
74036 802
802 99
© Meat
Meat &
& Livestock
Australia
©
Livestock australia
ABN 39
aBN
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